System effects on benzene removal from saturated soils and ground water using air sparging

This paper presents the results of a laboratory investigation performed to study the role of various air sparging system parameters on the removal of benzene from saturated soils and ground water. A series of one-dimensional column experiments was conducted with predetermined contaminant concentrations and predetermined injected air flow rates and pressures to investigate the effects of: (1) the soil type; (2) the use of pulsed air injection; and (3) the synergistic effects of co-contaminants on air sparging removal efficiency. This study demonstrated that the grain size of the soils affects the air sparging removal efficiency. A threshold value exists for effective particle size (D-10), which is equal to 0.2 mm; above this threshold value, the rate of removal is linearly proportional to the D-10 value; while below this value, there is a drastic increase in the time required for contaminant removal. Additionally, it was demonstrated that pulsed air injection did not offer any appreciable advantages over continuous injection for the coarse sand; however, pulsed air injection led to substantial reductions in system operating time for the fine sand. Finally, it was found that benzene and toluene existing alone had similar removal rates; however, they were removed slightly more quickly when they coexisted in the test soil.